Should I check for an empty RAM slot before upgrading my laptop's memory?

Yes, but only if your laptop has one soldered stick and one open SO-DIMM slot—common on ultrabooks and gaming laptops. Pop in another 16GB stick for 32GB total. If both sticks are soldered, you’re stuck. Check Task Manager or System Information for a “Slot 1 used, Slot 2 empty” situation, or crack it open if you’re comfortable. No slot means no upgrade—that’s the trade-off for thinness.